The Study Of Construction, Performance, And Mechanism On Heavy Metal Sorption Engineering Strains

The protoplast technology was used to breed the effective heavy metal sorption engineering strains in this research, including preparation of parental strains protoplast, protoplast-induction and protoplast-fusion of engineering strains, selection of mutants, capability and mechanism of sorption of mutants, toxicity experiment, and treatment of real wastewater, etc.The Cr6+-resistance mechanisms of four heavy metal sorption strains , namely Sporobolomycetaceae sp. 7-3, Sporobolomycetaceae roseus, Candida lipolytica, Candida utilis, and the toxicity of Cr6+ on them have been discussed elementarily. The results showed that acclimatization of Candida sp. was better than Sporobolomycetaceae sp., and the Cr6+-resistance of Sporobolomycetaceae sp. 7-3 was the best of the four. Removal of Cr6+ by Candida sp. was depended on both surface sorption and intracellular accumulation.The optimal condition of protoplast preparation of those four strains had been studied. Then ultraviolet and HNO2 were selected as the mutagens to perform induction mutation towards Candida utilis protoplast of CR-001. Six mutants which possessed high heavy metal removal efficiency and high resistance to Cr6+ were obtained. On the other hand , protoplast-electricity-induced fusion was used to construct high-efficiency heavy metal sorption strains. CRC2811-1 and R32 were used to treat real wastewater. The results showed that treatment effects of CRC2811-1 and R32 of three kinds of industry wastewater were better than the original strains before indution or fusion, especially of the planting wastewater. Furthermore, CRC2811-1 and R32 possessed adaptability, treatment ability and shock resistant ability to a lot of industry wastewater.The results of toxicity experiments showed that R32 would not cause acute, chronic, cumulative and genetical toxicity effect on algae, Allium cepa, Zebra, fish and mice before it absorbed Cr. The recovery and sterilization measurement in routine water treatment could reduce most of the R32 in effluent. This may ensure that the effluent would not cause any ill effect on all kinds of biology in the environment after it was discharged into the river.